Preheat broiler. Squeeze lime over both sides of steak; sprinkle with chili powder and rub with your hands. Place steak on a broiler pan and broil, 4 inches from heat, until medium-rare, about 4 to 5 minutes per side, or longer for desired degree of doneness. Let steak rest for a few minutes and then thinly slice against grain.

Meanwhile, separate clemetines into segments and roughly chop; place in a medium bowl and toss with cilantro, jalapeño and scallions.